To produce your on powder from raw materials you can take and mix any adequate powder you like from known powder producers as Hoeganaes or Ecka or H.C. Stark. You “simply” have to adequately adapt your powder and process parameters. A very sufficient material is for example a stainless steel as 17-4 PH as described (on page 3) of the attached file.

1) Concerning software you best contact http://www.scaps.de. They have done similar packages for stereolithography. Attached you find an RTCR5 manual in case you should be interested in writing your own.

2) Concerning a suitable scan head, it depends a little on the field size you want to process. Very roughly a hurrySCAN 20 with RTC5 will cost slightly more than 10,000 USD. High-speed versions with SiC mirrors or Beryllium (reduced scan angle) are more expensive.

3) I think EOS still sells the powder but I am not sure about the machine — at least it has been taken from their homepage.

Can you please also send us your phone number? Some things are easier to discuss on the phone.

Thank you very much for following up. What I’m am developing is basically an alternative system to the M270. I have been working with a job shop to make parts for a while and I am considering if it would be possible to make a custom system. The point your friend made about the power of the laser is consistent with some publications in materials science journals that describe the process of DMLS. They also say that CO2 lasers only work with metal mixes containing copper.

As I mentioned this will probably occur in two stages. I have a CO2 laser now and have developed CNC machines before. If I could perform DMLS with with a relatively simple prototype using copper-based powders, then I may go to a more advanced system with a higher power laser.

For software. No, I haven’t thought about it too much. In my other CNC systems I’ve used EMC2, an linux based software package. Its very flexible. I’ve assumed that I’d have to have custom software that converts .stl files to layered 2d scans. The EMC2 would probably coordinate between the scans running on a the commercial scanning software, and control the other DMLS steps to make a part.

Right now, in addition to just seeing how large the budget will be for this project, the biggest issue is obtaining the DMLS powder. If EOS is no longer selling the copper-based mix, the challenge will be to get that from somewhere else. I have contacted a couple of other researchers who have made DMLS powders in their laboratory.

Thanks for your Email. I talked to a friend who works for a company called EOS GmbH which pioneered that technology.

He said that with a 250 W CO2 laser you won’t get enough power density to melt typical metals. A few years ago they used to sell a CO2 laser based system with similar parameters as you describe them (nowadays these setups are only used for organic plastic materials). With such a setup you can only sinter special metal mixes that have a high portion of copper lowering the melting point — i.e. you will get for example some iron particles in a copper matrix. These systems have been discontinued when high power fiber laser have become available that allow much smaller spots and therefore a higher power density. He recommended their M270 system (see http://www.eos.info/en/products.html).

How large are the parts you want to produce? Have you thought about software? Of course we would be happy to sell you a scan head but I think it might be better to purchase an EOS system if you plan to operate it very often, or look for a job shop that uses their machines (I am sure EOS can put you in contact with some of their US customers).

I am not sure if I need an objective, if you could give me some details that would be helpful. For my application the spot size will be around 200-400 micron.

In part I am trying to decide if I should build the device in two stages. In the first (and cheaper) stage I was planning on focusing the beam using static collimating optics to determine if I can actually sinter the metal. I was planning on using more complex optics after determining that it is possible to sinter metal.

In either case, right now I am just trying to develop a preliminary budget, please don’t worry about exact numbers, I just want to work out the general costs.

Thanks for your email. How do you want to focus the laser beam? Do you need an objective? If speed is very important and if you should use an objective that clips the laser beam at a smaller scan angle (like telecentric objectives that are usually used to achieve a small spot size) than the hurrySCAN 20 offers, an intelliDRILL 20 scan head would also be interesting.

a fairly clear description of where to obtain HSS powder and how to combine with copper. I might explore this option.

I am confused about something I read in your article (Journal of Materials Processing Technology 141 (2003) 319-328) you performed post processing by raising to 1250 degrees under vacuum. Is this required or just meant to improve the densification?

Also, will it be useful to build a DMLS chamber to maintain a nitrogen atmosphere?

I see! I was the main developer of LaserTool. Actually, preparing a DMLS material is not very difficult if full densification is not a main object.

Simply by using fine and spherical powders (average size of about 30 micron) and employing a relatively high laser power (for CO2 250 W and for Nd:YAG 100 W) you should be able to reach density of 85-90 % theoretical for Bronze and Stainless steel powders. Please keep layer thickness as 50 micron and hatch spacing to 0.3 (25% overlap). Also, please use short scan vector. The other problem you may involve could be part cracking due to the thermal stresses. You may preheat the platform to reduce this problem.

Full densification is feasible if you use higher laser intensity to attain full melting of the powder bed.

Thank you for responding. For now, my application is not particularly complicated. There is interest here to simply see if we can set up DMLS capability to rapidly prototype parts with bronze or steel based powders. We have some equipment on hand and are prepared to purchase other parts of the system to create an initial prototype.

Were you involved in the construction of LaserTool? How difficult was it to make?

Thanks for your e-mail and your interest on DMLS powder. We have
patented LaserTool on 2001. At first EOS attracted our patent right
but later purchased it then shutdown the production (!) because the
price of this powder is less than 10% of the current available
materials produced by the company. It is understandable because as
the low amount of the material are used worldwide the high price
guarantee the benefits of the company.
You should enable to purchase the materials from EOS; you may send a
mail and ask. If it does not work, you may contact Dr. Frank Petzoldt
(fp@ifam.fraunhofer.de), the deputy director of Fraunhofer Institute
IFAM, Germany, and request the materials (either LaserTool or other
type which they have developed).

I don’t know in which application you intend to use the material. If
you give me more information I would be pleased to help.

I have read a number of your publications that evaluate the properties of DMLS materials and I was wondering if you could answer some questions.

I am considering construction of a custom made DMLS machine using a 250 watt C02 laser but I do not know of a source for DMLS powder. Your 2003 publication “On the development of direct metal laser sintering for rapid tooling” you describe the properties of LaserTool , is it possible to obtain this material?

If it is not available, do you have suggestions of how I could obtain DMLS powder from commercial manufacturers, or to fabricate DMLS powder from raw materials? I am assuming that EOS does not supply any of their DMLS powder to people that do not own one of their systems, perhaps this is an incorrect assumption.

Owen

Owen White, PhD

PI, Data Analysis and Coordination Center for the Human Microbiome Project
Director of Bioinformatics, Institute for Genome Sciences
Professor, Department of Epidemiology and Preventative Medicine
University of Maryland School of Medicine
801 West Baltimore Street, Room 661
Baltimore, MD, 21201